In semiconductor technology, component elements are known in which an electrode is used as a Schottky contact, such, for example, as Schottky field-effect transistors and Schottky diodes. These component elements are usually constructed in the following manner: On a substrate having a high ohmic resistance, which consists, for example, of semi-insulating gallium arsenide, a thin layer of a monocrystalline material is deposited by an epitaxial process, for example by gas-phase epitaxy, melting epitaxy, or by a molecular beam epitaxy. This thin layer of monocrystalline material represents the active layer of the component element. For the "Intern. Electronic Devices Meeting," Washington, D.C. (1975) Techn. Digest, pp. 585-587, a process is known in which a high-ohmic epitaxial layer is applied on a high-ohmic gallium arsenide substrate, and this high-ohmic layer is then doped with the aid of ion implantation. From "Electronic Letters" 9 (1973), pp. 577-578, a process is known in which the ion implantation into the high-ohmic substrate material is carried out, and in which a thinly doped layer is produced in this manner.
The semiconductor component elements in which an electrode consisting of a Schottky contact are distinguished by their short switching time. The switching characteristics of these component elements are, however, often unfavorably influenced by parasitic resistances which are present in the element. These resistances are occasioned by the active semiconductor layers used in these component elements, the thicknesses of which semiconductor layers generally lie in a range between 200 and 500 nm. These parasitic resistances show themselves to be obstructive particularly in the integration of Schottky field-effect transistors for logic circuits, since with circuits of this type the Schottky field-effect transistors are generally constructed as so-called "normally off" field effect transistors, in which the active layer has an even lesser thickness vis-a-vis the normal mode of construction. The thickness of the active layer is smaller in this type of component element than the thickness of the depletion layer of barrier which exists under the Schottky contact when no gate voltage is applied to it.
With the semiconductor material dopings of about 10.sup.17 cm.sup.-3 which are compatible with these demands of an element of this type, the thickness of the active layer, for example, with gallium arsenide, will amount to less than 100 nm. If, for example, with Schottky field-effect transistors, ohmic contacts for the source and drain electrodes are placed at both sides of the gate, then between these contacts and the active channel zone which is situated under the Schottky field-effect electrode of the component element, as a result of the very slight thickness of the layer through which the current flow occurs, there exists in each case a high feed line resistance, which may also be referred to as a series resistance. A corresponding situation is true as well for the ohmic contact to the semiconductor in a Schottky diode. As a result of such high series resistances, however, the high frequency characteristics and the switching times of the component element are strongly negatively influenced. It is an essential object in the construction of such component elements to minimize these series resistances. This can be achieved either in the doping, or in the thickness, or on the other hand, if possible, not only the doping but also the thickness of the parts of the active semiconductor layer serving as a feed line must be as large as possible.
It is possible to reduce the feed line resistances in that, according to a process known from "Solid-State Electronics" 18 (1975), pp. 977-981, a thin layer with a charge carrier concentration of about 7.multidot. 10.sup.18 cm.sup.-3 is produced in GaAs with the aid of an ion implantation of tellurium. A layer of this kind has, to be sure, a small series resistance for the ohmic contacts applied on it. However, no Schottky contact can be constructed in this kind of layer because such a high doping concentration would prevent the formation of a depletion layer in the region of the Schottky contact electrode.